Pressure indicator



A ril 26, 1966 RODGERS 3,247,824

PRESSURE INDICATOR Filed April 20, 1964 llc Nb Ila.

INVENTOR. ARTHUR RODGERS mafdza w A TTO/QVEYS United States Patent 3,247,824 PRESSURE INDICATOR Arthur Rodgers, Northhrook, IIL, assignor to The Fire Guard Corporation, a corporation of Illinois Filed Apr. 20, 1964, Ser. No. 361,023 8 Claims. (Cl. 116-70) This invention relates gene-rally to pressure indicators and more particularly to a novel pressure indicator preferably for use with fire extinguisher tanks.

There are many types of pressure indicators presently on the market for indicating the pressure in a fire extinguisher tank. These indicators usually operate over a range from zero to perhaps 175 p.s.i. A fire extinguisher tank is properly charged if the pressure resides within an upper range of, for example, from 120 p.s.i. to 175 p.s.i. Below 120 p.s.i., the tank is underpressurized and is of no use.

With the presently available pressure indicators, the indication varies linearly with the pressure over the entire range. Usually the degree of movement of the indicating element is relatively small between the fully charged condition and uncharged condition. As a consequence, there is relatively smaller movement between 120 p.s.i. and 175 p.s.i. and it is very difiicult to determine whether the extinguisher is fit for use or has lost its charging pressure when the actual pressure reading is in the neighborhood of 120 p.s.i.

With the foregoing in mind, it is accordingly a primary object of this invention to provide a novel pressure indicator in which the indicator will show a properly charged condition of a fire extinguisher tank as, for example, when the pressure is between 120 p.s.i. and 175 p.s.i. and immediately upon any pressure drop below a given threshold pressure such as 120 p.s.i., show an abrupt change. Accordingly, the user is never in any doubt about the suitability of the extinguisher for use.

Other important objects are to provide a pressure indicating device meeting the foregoing object which is rel tively economical to manufacture, is compact in size, and which is reliable in operation.

Briefly, these and other objects and advantages of this invention are attained by providing an indicating means adapted to indicate at least two different pressure conditions. Cooperating with this indicating means is a pressure responsive means for actuating the indicating means only when a given pressure threshold within a given pressure range is crossed. With the foregoing arrangement, a first condition is continuously indicated by the pressure indicator in response to all pressures in a given pressure range below a given pressure and a second condition is continuously indicated in response to all pressures in the given pressure range above said given pressure. Accordingly, a person may determine at a glance the condition of the fire extinguisher.

A better understanding of the invention will be had by now referring to a preferred embodiment thereof as illustrated in the accompanying drawings, in which:

FIGURE 1 is an exploded perspective view partly in crosssecti-on illustrating the basic component parts making up the pressure indicator;

FIGURE 2 is a partial cross-section of the various parts in assembled relationship; and,

FIGURE 3 shows in fragmentary view a modification of the pressure indicator.

Referring to both FIGURES 1 and 2, the pres-sure indicator comprises an externally threaded body for securement in the wall or cover of a pressurized vessel. The body 10 terminates at its lower end in key means 10a and 10b and also includes radially inwardly directed projection means lite and 10d terminating at their upper ends in sloping cam surfaces. The entire body 10 as 3,247,824 Patented Apr. 26, 1966 described may constitute a single integrally molded member.

Cooperating with the body 10 is a plunger 11 including at its lower ends lateral key ways 11a and 11b adapted to receive the key means 10a and 10b of the body 10 so that the plunger 11 is keyed against rotation with respect to the body 10 and yet may move longitudinally with respect thereto.

The upper end of the plunger 11 terminates in sloping cam surfaces 11c forming a circumferential ratchet configuration. The plunger 11 is responsive to pressure acting on its lower end to move longitudinally within the body 10.

A coupling means in the form of a floating detent element 12 is shown disposed above the plunger 11. The element '12 includes lateral projections 12a and 12b as shown. This element also includes a square crosssection central opening 120. The lateral projections 12a and 12b are adapted to seat on the cam surfaces of the upper end of the plunger 11 when the device is assembled as shown in FIGURE 2.

An indicating means in the form of a disc 13 having a square shaft 13a receivable within the square openings is coupled through the medium of the detent element 12 to the plunger 11. This indicating means includes on its upper face alternate sectors 13b of a specific color such as red, the remaining sectors 13c being of a different color such as green. A cover member 14 in turn has a surface divided into transparent alternate sectors 14a and opaque remaining sectors 14b. The arrangement is such that the transparent sectors v14a will register with the red colored sectors 13b of the disc 13 when the disc 13 is in a first rotative position whereas when the disc 13 is rotated through one-eighth of a complete rotation, the green colored sectors will be visible through the transparent portions 14a.

An upper spring 15 is positioned between the underside of the disc 13 and the top surface of the floating detent element 12 to bias this element downwardly so that the lateral projections 12a and 12b are pressed into engagement with the cam surfaces 110. With respect to the foregoing and as will be clear from FIGURE 2, when the detent element 12 is positioned so that its lateral projections engage the cam surfaces 110, the lateral projections will be disposed between the inwardly directed projecting means 10c on the body 10 so that the detent element 12 will be keyed against rotation.

A lower spring 16 is disposed beneath the projections 10c and 10d and the plunger 11 to oppose pressure acting to move the plunger longitudinally upwardly.

The assembly is completed by a suitable lower cover arranged to be fitted to the lower end of the body and retain the plunger in position, The lower end of this cover member terminates in a smooth bore including sealing O-ring 18 receiving a lower piston portion 11d of the plunger. This sealing ring insures a gas-tight connection with respect to the lower piston portion 11d so that longitudinal movement of the plunger may take place and yet a gas-tight seal can be maintained between the interior and exterior of the body.

The assembled structure as shown in FIGURE 2 illustrates the pressure indicating disc 13 in a first position to indicate a first pressure condition. In this condition, pressure acting on the plunger 11 at its lower end is below a given threshold pressure such as 120 p.s.i. In such condition, the red sectors 13b are visible through the cover 14.

In operation, assume that pressure exerted on the exterior of the lower piston portion 11d increases, thereby urging the plunger 11 upwardly against the force of the lower biasing spring 16. As this pressure increases, upward movement of the plunger 11 will cause the upper cam surfaces 11c to bear against the lateral projections 12a and 12b of the detent element 12 thereby urging the same upwardly. The plunger is keyed at 11a and 11b such that the cam surfaces 110 are engaged at mid positions. The spring pressure downwardly on the detent 12 tends to rotate the detent because of its engagement with the sloping cam surfaces 110. The detent element cannot rotate, however, because of the keying of the projections 120 with respect to the radially inward projections c and 10d on the body member 10.

As the upward movement of the plunger continues with increasing pressure, the detent element 12 will reach a level at which it is free of the inwardly directed projections 19c and 10d on the body member. When this oondition exists, the spring 15 exerting a downward pressure on the detent element will result in rotation of the detent element through approximately one-eighth of a turn until the projections 12a and 12b engage the vertical edges at the ends of the cam surfaces on the plunger 11. This rotation is a result of the detent riding down on the cam surfaces. As long as the plunger 11 is held in its upward position, the detent member will remain in its rotated position so that the green sectors are now visible through the transparent portions of the cover 14.

If the pressure should now drop so that the plunger 11 moves downwardly under force of the spring 16, the projections 12a and 12b of the detent member 12 will engage the sloping cam surfaces on the inwardly directed projections 10c and 10d of the body 10. As soon as the plunger has moved downwardly sufiiciently so that the vertical ends of the cam surfaces 11c leave the sides of the projections 12a, the detent will then rotate through another one-eighth turn to engage those upper cam surfaces of the plunger 11 space one-quarter of a turn from the first engaged cam surfaces. This further rotation through one-eighth of a turn is effected by the sloping cam surfaces on the projections 10c and 10d and results again in the red sectors being visible through the top cover and thus indicates that the pressure is now below a given threshold pressure.

It will be evident accordingly, that the pressure indicator will assume two pressure conditions and will remain continuously in a first one of these conditions as long as the pressure is below a given threshold pressure, and in a second one of these conditions as long as the pressure is above the given threshold pressure.

FIGURE 3 illustrates an alternative sealing arrangement to that illustrated in FIGURES 1 and 2. Thus, rather than an O-ring seal, a diaphragm 19 may be secured to the exterior lower portion of the cover 17 on the body 10 to cover the lower end of the plunger 11. Pressure acting on this diaphragm will then be transmitted to the plunger to move the same as described heretofore.

From the foregoing description, it will thus be evident that the present invention has provided a greatly improved pressure indicator. The entire structure consists of only nine basic parts, each of which may be easily manufactured. Moreover, the cooperating components may be made relatively small so that a compact configuration results.

While the invention has been described in conjunction with use for fire extinguishers, it should be understood that the indicator may be used in other environments in which it is desired to indicate whether or not a given pressure has dropped below a desired threshold value.

What I claim is:

1. A pressure indicator comprising, in combination: a body; an indicating means adapted to indicate at least two different pressure conditions; a pressure responsive means in said body adapted to move over a given distance in response to a variation in pressure over a given range; and coupling means for coupling said pressure responsive means to said indicating means to change said indicating means abruptly from a first one of said pressure conditions to a second one of said pressure conditions when a given pressure in said given range is exceeded, whereby a first condition is continuously indicated in response to all pressures in said given range below said given pressure and a second condition is continuously indicated in response to all pressures in said given range above said given pressure, said pressure responsive means comprising a plunger longitudinally movable in said body in response to pressure acting thereon; means keying said plunger to said body against rotational movement relative to said body, the upper end of said plunger terminating in a first sloping cam surface; and a lower spring biasing said plunger in a direction opposed to said pressure, said coupling means comr prising a detent element having at least one lateral projection the lower end of which engages said sloping cam surface, said body having radially inwardly directed projection means of given length in a longitudinal direction and terminating in an upper second sloping cam surface receiving said lateral projection to prevent rotation of said detent element which in a first longitudinal position, said indicating means being coupled for rotational movement with said detent element; and an upper spring biasing said detent element against said first sloping cam surface, whereby longitudinal movement of said plunger in response to increasing pressure urges said detent element upwardly in a longitudinal direction until its lateral projection is free of said inwardly directed projection means on said body at which time said element is free to rotate by movement along said sloping cam surface to thereby change said indicating means from said first condition to said second condition, downward movement of said plunger resulting in said lateral projection engaging said second cam surface on the upper end of said inwardly directed projection means to thereby result in a further rotation of said element to indicate said first condition.

2. A pressure indicator according to claim 1, in which said indicating means includes a rotatable disc having a face divided into sectors, alternate sectors being of a first color and the remaining sectors being of a second color, said disc having a square cross-section shaft coupled to said detent element for rotation therewith but permitting free longitudinal movement of said detent element relative thereto; and a cover member having a face divided into cover sectors, alternate cover sectors being transparent to expose said alternate sectors of said disc when said disc is in said first pressure indicating condition, the remaining cover sectors being opaque to eclipse said remaining sectors on said disc when said disc is in said first pressure indicating condition, rotation of said detent means rotating said disc to expose said remaining sector portions and eclipse said first mentioned alternate sector portions thereby indicating said second pressure condition.

3. A pressure indicator according to claim 2, in which the lower end of said plunger terminates in a piston portion, the lower end of said body terminating in a smooth bore through which said piston portion passes; and an O-ring in said bore to provide a substantially gas tight seal between the interior and exterior of said body.

4. A pressure indicator according to claim 2, in which the lower end of said plunger terminates in a pressure responsive surface protruding from the lower end of said body; and a diaphragm covering the lower end of said plunger and secured to the exterior of said body whereby a substantially gas tight seal between the interior and exterior of said body is provided.

5. A pressure indicator comprising, in combination: rotative indicating means adapted to indicate at least two different pressure conditions, said indicating means including a rectilinear shaft; pressure responsive means designed for longitudinal movement in a direction co-axial with said shaft; coupling means interconnecting said pressure responsive means to said indicating means, said coupling means converting said longitudinal movement of said pressure responsive means into rotative movement of said indicating means; and, spring means biasing said pressure responsive means to a first position corresponding to one of said pressure conditions, the force of said spring means being overcome in response to the other of said given pressure conditionsto efifect longitudinal move ment of said pressure responsive means to effect corresponding rotative movement of said indicating means, said coupling means including locking means preventing any movement of said indicating means until said other predetermined pressure condition is reached.

6. A pressure indicator, according to claim 5, in which said coupling means includes inclined cam surfaces for efiecting conversion of said longitudinal movement of said pressure responsive means into rotative movement of said indicating means.

7. A pressure indicator, according to claim 5, in which said indicating means includes a rotatable disc having a face divided into sectors, alternate sectors being of a first color and the remaining sectors being of a second color; and a covering member having a face divided into cover sectors, alternate cover sectors being transparent to expose said first color on said alternate sectors of said disc when said disc is in a first rotative position, the remaining cover sectors being opaque to eclipse said second color on said remaining sectors on said disc, rotational movement of said disc taking place upon actuation thereof by said pressure responsive means to expose said second color and eclipse said firs-t color.

8. A pressure indicator comprising, in combination: a body; a rotative indicating means adapted to indicate at least two different pressure conditions, said indicating means including a rectilinear shaft; a pressure responsive means designed for longitudinal movement in a direction co-axial with said shaft; a coupling means interconnecting said pressure responsive means to said indicating means, said coupling means converting said longitudinal movement of said pressure responsive means into rotative movement of said indicating means, said pressure responsive means being designed for movement within said body; and, spring means urging said pressure responsive means to a first position corresponding to one of said pressure conditions, said spring means being overcome by a change in pressure to the other of said given pressure conditions whereby longitudinal movement of said pressure responsive means is effected to in turn cause rotative movement of said indicating means, said coupling means including locking means preventing any movement of said indicating means until said other predetermined pressure condition is reached.

References (Iited by the Examiner UNITED STATES PATENTS 1,611,659 12/1926 Malivert 116117 2,188,177 1/1940 Dube 73-410 2,650,561 9/1953 Seid et al. 1161l7 2,827,122 3/1958 Clark 116ll4.17 2,850,900 9/1958 Billington 73-406 3,110,284 11/1963 Napier 116-129 LOUIS I. CAPOZI, Primary Examiner. 

1. A PRESSURE INDICATOR COMPRISING, IN COMBINATION: A BODY; AN INDICATING MEANS ADAPTED TO INDICATE AT LEAST TWO DIFFERENT PRESSURE CONDITIONS; A PRESSURE RESPONSIVE MEANS IN SAID BODY ADAPTED TO MOVE OVER A GIVEN DISTANCE IN RESPONSE TO A VARIATION IN PRESSURE OVER A GIVEN RANGE; AND COUPLING MEANS FOR COUPLING SAID PRESSURE RESPONSIVE MEANS TO SAID INDICATING MEANS TO CHANGE SAID SURE CONDITIONS TO A SECOND ONE OF SAID PRESSURE CONDITIONS WHEN A GIVEN PRESSURE IN SAID GIVEN RANGE IS EXCEEDED, WHEREBY A FIRST CONDITION IS CONTINUOUSLY INDICATED IN RESPONSE TO ALL PRESSURES IN SAID GIVEN RANGE BELOW SAID GIVEN PRESSURE AND A SECOND CONDITION IS CONTINUOUSLY INDICATED IN RESPONSE TO ALL PRESSURES IN SAID GIVEN RANGE ABOVE SAID GIVEN PRESSURE, SAID PRESSURE RESPONSIVE MEANS COMPRISING A PLUNGER LONGITUDINALLY MOVABLE IN SAID BODY IN RESPONSE TO PRESSURE ACTING THEREON; MEANS KEYING SAID PLUNGER TO SAID BODY AGAINST ROTATIONAL MOVEMENT RELATIVE TO SAID BODY, THE UPPER END OF SAID PLUNGER TERMINATING IN A FIRST SLOPING CAM SURFACE; AND A LOWER SPRING BIASING SAID PLUNGER IN A DIRECTION OPPOSED TO SAID PRESSURE, SAID COUPLING MEANS COMPRISING A DETENT ELEMENT HAVING AT LEAST ONE LATERAL PROJECTION THE LOWER END OF WHICH ENGAGES SAID SLOPING CAM SURFACE, SAID BODY HAVING RADIALLY INWARDLY DIRECTED PROJECTION MEANS OF GIVEN LENGTH IN A LONGITUDINAL DIRECTION AND TERMINATING IN AN UPPER SECOND SLOPING CAM SURFACE RECEIVING SAID LATERAL PROJECTION TO PREVENT ROTATION OF SAID DETENT ELEMENT WHICH IN A FIRST LONGITUDINAL POSITION, SAID INDICATING MEANS BEING COUPLED FOR ROTATIONAL MOVEMENT WITH SAID DETENT ELEMENT; AND AN UPPER SPRING BIASING SAID DETENT ELEMENT AGAINST SAID FIRST SLOPING CAM SURFACE, WHEREBY LONGITUDINAL MOVEMENT OF SAID PLUNGER IN RESPONSE TO INCREASING PRESSURE URGES SAID DETENT ELEMENT UPWARDLY IN A LONGITUDINAL DIRECTION UNTIL ITS LATERAL PROJECTION IS FREE OF SAID INWARDLY DIRECTED PROJECTION MEANS ON SAID BODY AT WHICH TIME SAID ELEMENT IS FREE TO ROTATE BY MOVEMENT ALONG SAID SLOPING CAM SURFACE TO THEREBY CHANGE SAID INDICATING MEANS FROM SAID FIRST CONDITION TO SAID SECOND CONDITION, DOWNWARD MOVEMENT OF SAID PLUNGER RESULTING IN SAID LATERAL PROJECTION ENGAGING SAID SECOND CAM SURFACE ON THE UPPER END OF SAID INWARDLY DIRECTED PROJECTION MEANS TO THEREBY RESULT IN A FURTHER ROTATION OF SAID ELEMENT TO INDICATE SAID FIRST CONDITION. 